At least 142 Pakistanis, mostly of the minority Ahmadiya community, arrested in police sweeps in Sri Lanka in June 2014 are being detained and are at risk of deportation, the Human Rights Watch said.
"Sri Lankan authorities are threatening Pakistani minority group members with deportation at the very time when persecution of these groups is escalating in Pakistan," said Bill Frelick, refugees director at Human Rights Watch.
"Preventing asylum seekers from lodging claims in no way absolves Sri Lanka from its duty not to return them to possible persecution," he added.
The sweeps of Pakistani minority neighbourhoods in Negombo, a city on the western coast of Sri Lanka, began on June 9, with authorities citing security concerns for the sweep.
Negombo has been a haven for minority refugees from Pakistan. In 2013, UNHCR registered nearly 1,500 refugee claims of Pakistanis in Sri Lanka.
"Sri Lankan authorities should know that Pakistan fails to protect its minority communities from persecution. Sri Lanka must honor its international obligations, and allow UNHCR access to ensure that no detainee is deported to face the risk of persecution or torture," Frelick said.